


Quantitative

by eloquated



Category: Sherlock (TV)
Genre: Gen, Introspection, Kidlock, Teenlock, but you'd have to squint, could be seen as pre-slash
Language: English
Status: Completed
Published: 2018-10-04
Updated: 2018-10-04
Packaged: 2019-07-25 05:25:23
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,457
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16190987
Author URL: https://archiveofourown.org/users/eloquated/pseuds/eloquated
Summary: The seven years between them has no impact on their genetics.  That’s nature, ingrained under the skin and stitched in long chains of Deoxyribonucleic acid.  Deeper than blood or flesh, it’s the filling of their marrow.The rest is nurture.





	Quantitative

**Author's Note:**

> This idea has been bouncing around in my head for days, so obviously it wasn't going to just hush and leave me alone!
> 
> Besides, can't we all use a little Holmes brothers goodness to perk up the mid week?

On a chemical level they are the same.  DNA in long chain helixes, all of their possible potential coded into microscopic cells.  A million combinations and variables, a genetic melting pot of pigments and defects assigned with random luck to create the heirs of the Holmes name.

Mycroft inherited the damaged MC1R protein from both of his parents; his hair is auburn and copper, and melaninized cells that have covered his skin with constellations of freckles in cinnamon and sand.

Neither of their bodies can break down acetaldehyde-- but their parent’s can.  They aren’t sure which side of the family it came from, Uncle Rudy and Aunt Rosemary can’t, either.  But they’re on separate sides. Sherlock doesn’t care that he flushes when he drinks, but Mycroft finds the mottled blush embarrassing.

They have the same recessive eyes, in different blues.  

The same ears.  The same hands with their long, tapering fingers and squared palms.  And when Sherlock is four, he doesn’t understand how they can have the same parents when they look so dissimilar.  For a year he’s fascinated with genetics; and who better to answer his questions than his own genetic mirror, and holder of a different collection of their shared potential?

It’s the same rare AB blood in their veins.  

Sometimes, Sherlock tells his brother that he’s keeping him around for spare parts.  “Be careful with that liver.. those kidneys... You’re just keeping them fresh for me.”  Mycroft is mostly sure that he’s kidding. The alternative is too monstrously callous, even for Sherlock at his worst.

Mycroft is equally sure that, should his brother have need of them, that he would offer them up without moment of hesitation.

The seven years between them has no impact on their genetics.  That’s nature, ingrained under the skin and stitched in long chains of Deoxyribonucleic acid.  Deeper than blood or flesh, it’s the filling of their marrow.

The rest is nurture.  

It was Mycroft at seven, staring through the bars of his brother’s crib and realizing for the first time in his life that there was someone like him.  Even then, Mycroft knew his brother was special; so much more than their aunts and uncles cooing over his dark curls and bright eyes. 

He was like Mycroft.  Brilliant, different from the others; and even though he was too young to understand the weight of his promise, Mycroft swore he wouldn’t let his brother know how lonely those differences could be.

When he was four, Sherlock refused to learn to read.  Mycroft supposed being contrary was more of an affectation than a genetic trait, but it seemed to be part of his brother’s nature all the same.  He watched his parents beg and threaten and bribe, only to be met with a lisped and emphatic, “NO.” And the latest card paged book thrown as far across the room as Sherlock’s skinny arms could manage.

Mycroft couldn’t blame him, not really.  He’d hated those books, too. “See Spot. See Spot run.  Run Spot, run.” As if either of them cared a whit for the athletic prowess of a drawn dog with, predictably, spots.  Instead, Mycroft had taken one of his own books from the shelf, and planted his little brother on the couch beside him.  

“I’m not reading, I won’t, I won’t!”  Sherlock had started, his lisped voice rising on each odd syllable.  At eleven, Mycroft just put his hand over his brother’s mouth, and grinned, “No.  I’m going to read to you. Now be quiet and listen.. Chapter One, In which Cimorene refuses to be proper, and has a conversation with a frog..”

By the end of the first chapter, Sherlock had crawled into his brother’s lap to look at the words.  And by the time the wizards had started to cause trouble, he was following the lines of well-worn text with the tip of his finger.  After that, things started to go more smoothly, but for a long time after, Sherlock would pretend he’d forgotten how to read. His arms filled with books, he would invade Mycroft’s room and demand to be read to.

Most of the time, he did.  And by Christmas, they’d rescued King Mendanbar from the wizards, Narnia from the White Witch, and were well on their way to helping Bilbo Baggins outwit the terrible Gollum in his dark and dripping cave.

Nature was Mycroft turning thirteen and everything starting to change.  It was the nature of the beast that he had more school work and less time; that the world was expecting more from him, now.  There were expectations, and the pressure to put down things that were considered too childish, now that he was becoming a young man.

It was in Sherlock rebelling against the school and the system that was taking his brother away.  They were too stupid, all of them, and they never let him break the rules, so why could they? Mycroft was his, his brother, his person; and Sherlock despised their pacifying explanations about getting older and growing up.

“You’re not allowed to go, it’s not fair, and I won’t let you.”  He’d stated when he was nine, and Mycroft was sixteen. There was a suitcase open on the bed, already half filled with his big brother’s clothes and the things he would need at university.  And Sherlock wasn’t afraid, or sad, he was furious. His own brother had made those rules, and promised he wouldn’t leave him.

Now he was going away, and Sherlock wouldn’t see him until the mid term break.  Nine weeks had never seemed like such a long time, and what was he supposed to do?  Just sit and wait? “I won’t! You’ll go away, and I’ll hate you, I’ll never speak to you again!”  

Mycroft hadn’t looked hurt, and Sherlock spent the whole drive to Cambridge with his arms locked around his brother’s.  “I’m scared, too. It’s part of getting older, things change, even if we don’t particularly want them to. But I will always be your brother, it’s in our blood, and even we can’t change that.”  

Neither of them thrived on sentiment, but this was science.  Factual. Quantitative data that he could measure and compare; like being four again and holding his hands up to Mycroft’s to compare the shapes of their bones.  He knows his own are still soft, still growing. But soon, he reminds himself, they’ll slow and stop, and he will be made permanent.

There’s something comforting in that.

Nature is slamming into puberty when he’s fourteen, and hating the way his voice cracks and breaks.  He’s almost as tall as his brother, and Sherlock isn’t quite sure if he’ll ever outgrow him. He wants to-- wants Mycroft to have to look up to him for a change.  

Because he’s twenty-one now, and his suits fit better, and he ruffles Sherlock’s curls when he hugs him hello.  And Sherlock is angry at the world for being so bitterly unfair, and ducks away because he knows his brother is going to leave again.  Even though he always takes the extra few days off, every year, so he doesn’t have to go before Sherlock’s birthday.

Sherlock feels trapped and fractious in his own skin, and before he leaves, Mycroft promises him that that, in time, will pass too.

For Mycroft, it’s neither nature, or nurture, but inevitability that sets him behind a desk.  He’d always known he would end up here, climbing the invisible ladder and wrapping strings around his fingers as he ascends.  His childhood walls have turned into a fortress, and Sherlock takes delight in smashing brother-shaped holes in his defenses.

They pick, and pick, looking for weaknesses and marking them for later.  And in the quiet after Sherlock’s first overdose, they try to discover who they are as adults.  What had endured the tectonic shift of adolescence and distance, and what had become too damaged to salvage.

They rebuild from the rubble, because both of them are too stubborn to give up.  Maybe it’s the iron in their blood, Sherlock theorizes as he shakes and sweats through the withdrawal; or magnets that had been stuck together for so long that their electrons had aligned.

Mycroft doesn’t correct his science.  He doesn’t remind his brother that friction between two magnets can be devastating for them both.  Neither of them is that flexible, their poles are fixed points. And he doesn’t know what that means for them.

They have moved beyond the tangible, the quantitative, and into the theoretical.

In the dark, Sherlock reaches up from the bed, and Mycroft is reminded of being seven again, and the revelation of not being alone.  They have the same eyes, in different blues.

Some things are permanent… and that’s enough for now.


End file.
